The present invention relates to the actuation and de-actuation of cylinders of an internal combustion engine by deactivation and activation of the gas-changing valve of the respective cylinder.
U.S. Pat. No. 5,787,855 discloses a switching off of cylinder groups of an internal combustion engine by deactivation of the gas-changing valve. With motors with many cylinders, a driving situation exists in which the required power can be provided from a part of the cylinder. The switching off of one or more cylinders leads to the situation that the remaining operating cylinders are operated with an increased power and better efficiency. EP 37269 likewise shows a switching off of gas-changing valves. A continuous production of the valve stroke is known from DE 195 01 386.
The deactivation and activation of cylinders should be as undetectable as possible for the driver. In particular, no irregular moment of rotation change should occur upon changing between complete engine operation in which all cylinders operate and partial engine operation, in which at least one cylinder is switched off.
The present invention is based on the problem of realizing the most simple, undetectable switching on and off of cylinders as possible for the driver.
According to the present invention, the change between full engine operation and partial engine operation of a multi-cylinder internal combustion engine, in which at least the intake valve or the escape valve of a cylinder or a group of cylinders in full engine operation are activated and in partial engine operation, are deactivated. In a first step, a throttling of the power of the cylinder to be deactivated takes place and simultaneously, an increased of the power of the other cylinders takes place, so that the total moment provided from the engine follows a provided desired engine moment. In a second step, a switching off of the throttled cylinder takes place via the actuatable intake or escape valve of this cylinder.
For reactivation of the switched-off cylinder, that is, for changing from partial engine operation to full engine operation, a switching-on of the throttled cylinder takes place in a first step via the actuatable intake or escape valve and in a second step, an unthrottling of the power of the cylinder to be reactivate takes place, along with a simultaneous reduction of the power of the other cylinders, so that the total moment provided from the engine follows a provided ideal engine moment.
With the above-described process, the advantage is provided that the change between partial and full engine operation does not occur through a sudden, abrupt and detectable actuation. In addition, the shift of the moment of rotation preparation from all cylinders on a part of the cylinder is at least approximately uniform and substantially temporal.
In this manner, particular advantages with variable valve controls with high temporal tolerances in switching-off operation is provided, which will be described below.
The change between partial and full engine operation and from full- to partial engine operation is accomplished through a control command. Between the time point of the change by means of the control command and the time point to which the changing is effective, a known time interval elapses, which is dependent on the constructive qualities of the valve control. A high tolerance or measure of deviation of this time interval has the result that between the change of the rotational moment from the other cylinders and the effective change between both types of engine operation, a time difference can occur, so that the changing over is detectable in an unwanted manner by the driver. Systems, for example, in which a variable valve stroke is determined by means of the relative positions of an opening cam shaft and a closing cam shaft, which are connected by means of a mechanical coupling gear, can have such temporal tolerances. A system with opening and closing cam shafts is described in the previously noted DE 195 01 386. The temporal range and uniformity of the shift between the cylinders provides, therefore, that also with temporal differences between the reduction of the moment of rotation of the cylinder to be switched off and the increase of the moment of rotation of the cylinders to be further operated, the entire moment of rotation change of a cylinder group is never suddenly operative.
One form of the invention contemplates that an internal combustion engine includes a respective throttle valve or flap for the cylinder to be switched off as well as the cylinders to be further operated, or an individual throttle valve. In this embodiment example, the throttle of the power of the cylinder to be deactivated takes place via a closing of the associated first throttle device and the increase of the power of the cylinders to be further operated takes place via an opening of the throttle device of the associated cylinders to be further operated.
To re-actuate the switched-off cylinder, an un-throttling of the cylinder to be reactivated takes place by means of an opening of the first throttle device and a reduction of the power of the remaining cylinders via a reduced opening of the throttle device of the remaining cylinders.
This provides the advantage that the invention can be used also with valve operations, whose opening stroke can be determined only digitally between zero and completely open.
A further form of the invention relates to an internal combustion engine with uniform or at least finely-staged adjustable stroke of the intake valve. Here, the throttling of the power of the cylinder to be deactivated takes place via a reduction of the lift of its intake valve, and the increase of the power of the cylinder to be further operated takes place via an enlargement of the lift of its intake valve.
For reactivating the deactivated cylinder, an un-throttling of this cylinder takes place via an increase of the stroke of the intake place to be reactivated and a reduction of the power of the remaining cylinders takes place via a reduction of the stroke of the intake valve of the remaining cylinders.
Therefore, a further, separate throttle device is insurable, as is required in the subject matter of the other embodiment described above.
Further advantages are provided with engines with a control apparatus for switching off of the cylinders and the re-operating of the cylinders: these types of control apparatus are typically connected with a bus system. The information is exchanged via the bus system non-synchronously with the calculating program of the individual control apparatus, which runs synchronously with the movement of the crank shat of the engine. With a digital switching off of the cylinder groups, a time slowing of the digital increase of the power of the other cylinder groups can take place, which the driver detects as a jolt or jerk.
With the invention, in contrast, a digital switching does not take place, rather, a uniform transition. Because of the uniformity of the transition, no jolt or jerk occurs, when a control apparatus begins this uniform transition somewhat earlier than the other control apparatus of the counter-running transition.
In conclusion, the invention affects an optimization of the uniformity of the moment of rotation upon changing between full and partial engine operation with minimal demands on the constructive complication of the switching-off of the valve.
The invention is directed also at an electronic control device for performing at least one of the above-described methods or one of the above embodiments.